From owner-freebsd-fs@freebsd.org Wed May 18 08:02:01 2016 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5AE76B40896 for ; Wed, 18 May 2016 08:02:01 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: from mail-wm0-x233.google.com (mail-wm0-x233.google.com [IPv6:2a00:1450:400c:c09::233]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id E057D18E7 for ; Wed, 18 May 2016 08:02:00 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: by mail-wm0-x233.google.com with SMTP id r12so21754004wme.0 for ; Wed, 18 May 2016 01:02:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=multiplay-co-uk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to; bh=26hb0lp5WcDOWlKZd+27ZAvGaHKfswna5DuPsFPGHko=; b=q0Jxo0h4mtYVNfQr2pPmuc7vw+/biv32ehLgHGJHz+5+FdN79JW5N2DeodqKdtaU72 OX8pHXRG8uNYz9BYohtyzKxSLir+pPS2rLZtbG/LsCjJUSROY34a2wCmO7u3NVw9yLcn DCMArqjco6bhVYKen3A0AWaiMThJV/BFbm1qTuMPMI92rZNOjArmyjfD3NyluL+p/bpk 8XnaVvtsvmtgoD82BCJmTwyMi2qvFZcB0ylwWBoIbhC9TvIok3R6v6ftdi6sz9Odckoa Vvpw9R1sD/C4sLK6kJlZ04pZPex8M1P5LPDGpIKD2RcWIBQriralpERP7fJc9X4Q5Np7 gxUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to; bh=26hb0lp5WcDOWlKZd+27ZAvGaHKfswna5DuPsFPGHko=; b=CbuUgs0GUHflFXCZH+19zhciUvQc+vBXHDr7hvxvJM5q2DwxpXd62jwwT/QBn+OIgB URxwwhzgFA/YmVlVqM93AUBL+gF7rGjW+NHfAv8wgx6Shy3hhlIA6hqW6HSgur4RdLEA sAfkJ2V3PV7t6MaAnsgF7xTT3r6KIaoYic9USLcHt+UNqIcE43l/PZ2LtdzdGDvWGe8S FljCAY1Yq0IkVujzGXQZwlNzlBxvYB1gODp0ZeAtgd2g/+q/Q8iZbdL6vJviMNmn6l1B erDTArXGlf4mTLeB2MkqnZxLX5DiOFdfyct6mZXhES1SYb+23fbJV5IteJnIw+vbreWr e1wA== X-Gm-Message-State: AOPr4FUVrakDx+YHxEtJqDTbk98DawlbRHJXG9Fo9r3+azF7od5IB2O+htPkgo6IOQodqec9 X-Received: by 10.28.111.14 with SMTP id k14mr6000521wmc.32.1463558518998; Wed, 18 May 2016 01:01:58 -0700 (PDT) Received: from [10.10.1.58] (liv3d.labs.multiplay.co.uk. [82.69.141.171]) by smtp.gmail.com with ESMTPSA id w9sm28180175wme.19.2016.05.18.01.01.57 for (version=TLSv1/SSLv3 cipher=OTHER); Wed, 18 May 2016 01:01:57 -0700 (PDT) Subject: Re: ZFS performance bottlenecks: CPU or RAM or anything else? To: freebsd-fs@freebsd.org References: <8441f4c0-f8d1-f540-b928-7ae60998ba8e@lexa.ru> <16e474da-6b20-2e51-9981-3c262eaff350@lexa.ru> <1e012e43-a49b-6923-3f0a-ee77a5c8fa70@lexa.ru> <86shxgsdzh.fsf@WorkBox.Home> From: Steven Hartland Message-ID: <39be913e-32a5-2120-fee5-4521b8b95d80@multiplay.co.uk> Date: Wed, 18 May 2016 09:02:03 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.22 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 May 2016 08:02:01 -0000 My comment was targeted under the assumption of random IOPs workload, which is typically the case, where each RAIDZ group (vdev) will give approximately a single drive performance. For a pretty definitive guide / answer see: http://blog.delphix.com/matt/2014/06/06/zfs-stripe-width/ There's also some useful practical test results here: https://calomel.org/zfs_raid_speed_capacity.html On 18/05/2016 05:21, Alex Tutubalin wrote: > On 5/18/2016 12:11 AM, Steven Hartland wrote: >> Raidz is limited essential limited to a single drive performance per >> dev for read and write while mirror is single drive performance for >> write its number of drives for read. Don't forget mirror is not >> limited to two it can be three, four or more; so if you need more >> read throughput you can add drives to the mirror. > > Do I understand it correctly: > > - single write of one large file (or singe local write to zvol shared > via iSCSI) will be local: single or only several metaslabs > > - for RAIDZ each disk will get only part of throughput > > - for mirror, each disk included in write will receive full data size > (and for single local write only limited number of disks to be > included in write) > > If so, raidz will have huge write performance benefit in my case: > single write of one large file. > > As for read speed, I hope to deal with it with large enough L2ARC on > SSDs. > > >> >> To increase raidz performance you need to add more vdevs. While this >> doesn't have to be double i.e. the same vdev config as the first it >> generally a good idea. > > Again, multiple vdevs will help for multiple parallel writes, but not > for single one? > > Alex Tutubalin > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"